Before optical elements, such as lenses, are assembled into lens modules, its refractive index must be measured to confirm performance of the lens. Generally, the refractive index of the optical elements is measured via a typical V-shaped prism measuring method. One requisite condition is that a V-shaped prism used in the method has two plane being perpendicular to each other if using the V-shaped prism measuring method. However, optical elements molded by conventional injection molding device do not meet this requirement. Therefore, the optical elements must be re-machined, which is time-consuming and inefficient.
It is therefore desired to provide an injection molding device, which can overcome the above-described deficiency.